test(@angular/build): add e2e for a larger project with Vitest

Adds an end-to-end test to verify Vitest runner performance and correctness
with a larger number of generated components, services, and pipes. This test
executes the suite in both JSDOM and browser environments to ensure stability
and proper functionality under scale.

(cherry picked from commit 960c80c)

Author: clydin

tests/legacy-cli/e2e/tests/vitest/larger-project.ts

@@ -0,0 +1,60 @@
+import { ng } from '../../utils/process';
+import { applyVitestBuilder } from '../../utils/vitest';
+import assert from 'node:assert';
+import { installPackage } from '../../utils/packages';
+import { exec } from '../../utils/process';
+
+export default async function () {
+  await applyVitestBuilder();
+
+  const artifactCount = 100;
+  // A new project starts with 1 test file (app.spec.ts)
+  // Each generated artifact will add one more test file.
+  const initialTestCount = 1;
+
+  // Generate a mix of components, services, and pipes
+  for (let i = 0; i < artifactCount; i++) {
+    const type = i % 3;
+    const name = `test-artifact-${i}`;
+    let generateType;
+
+    switch (type) {
+      case 0:
+        generateType = 'component';
+        break;
+      case 1:
+        generateType = 'service';
+        break;
+      default:
+        generateType = 'pipe';
+        break;
+    }
+
+    await ng('generate', generateType, name, '--skip-tests=false');
+  }
+
+  const totalTests = initialTestCount + artifactCount;
+  const expectedMessage = new RegExp(`${totalTests} passed`);
+
+  // Run tests in default (JSDOM) mode
+  const { stdout: jsdomStdout } = await ng('test', '--no-watch');
+  assert.match(jsdomStdout, expectedMessage, `Expected ${totalTests} tests to pass in JSDOM mode.`);
+
+  // Setup for browser mode
+  await installPackage('playwright@1');
+  await installPackage('@vitest/browser-playwright@4');
+  await exec('npx', 'playwright', 'install', 'chromium', '--only-shell');
+
+  // Run tests in browser mode
+  const { stdout: browserStdout } = await ng(
+    'test',
+    '--no-watch',
+    '--browsers',
+    'ChromiumHeadless',
+  );
+  assert.match(
+    browserStdout,
+    expectedMessage,
+    `Expected ${totalTests} tests to pass in browser mode.`,
+  );
+}